A Gigabit-Capable Passive Optical Network (GPON) technology is an important technical branch of the passive optical network (PON) family, and similar to other PON technologies, the GPON is also a passive optical access technology employing a point to multipoint topological structure.
The GPON is composed of an Optical Line Terminal (OLT) of a network side, an Optical Network Unit (ONU) of a user side, and an Optical Distribution Network (ODN), which generally employs a point to multipoint network structure. The ODN is composed of a single mode fiber, an optical splitter and an optical connector, and used to provide an optical transmission medium for the physical connection between the OLT and the ONU.
In order to realize a part of management functions to the ONU by the OLT, ITU-T G.984.3 standards defines a Physical Layer Operations, Administration and Maintenance (PLOAM) channel, and the GPON utilizes the PLOAM channel to transmit a PLOAM message, so as to realize the management for a transmission convergence layer, including an ONU activation, establishment of an ONU management control channel, an encryption configuration and a key management, etc. The PLOAM message is transmitted in an upstream frame (the frame sent from the ONU to the OLT) and a downstream frame (the frame sent from the OLT to the ONU), each downstream frame includes one PLOAM message, and the OLT determines whether the PLOAM message is included in the upstream frame. The GPON defines that the number of downstream PLOAM (Physical layer Operations, Administration and Maintenance downstream, shorten for PLOAMd) messages which are sent from the OLT to the ONU is 18, and the number of upstream PLOAM (Physical layer Operations, Administration and Maintenance upstream, shorten for PLOAMu) messages which are sent from the ONU to the OLT is 9. The name of one upstream PLOAM message sent from the ONU to the OLT is Dying_Gasp, and the production and function of that PLOAM message are: when the ONU is power off normally and receives an upstream burst timeslot (in which, the upstream burst timeslot is used for the ONU to send the upstream data) allocated by the OLT, the ONU turns on its own laser in the upstream burst timeslot that belongs to itself, and the ONU sends one Dying_Gasp message to the OLT to inform the OLT that the ONU itself has been power off normally, so as to prevent the OLT from sending an unnecessary alarm report. The ONU needs to wait for three burst timeslots allocated by the OLT after the power supply of the ONU is turned off, the ONU turns on its own laser in each burst timeslot, sends one Dying_Gasp message and sends GPON Encapsulation Method (GEM) frame in the residual bandwidth of the current burst timeslot (if the ONU has no effective data to be sent in the residual bandwidth, then the ONU sends an idle frame to the OLT), and the ONU turns off it own laser when the upstream burst timeslot belonged to itself ends. It requires that, after the ONU turns off the power supply, an electric supply installation of the ONU can support the ONU to finish the transmission of the above data, which needs a higher requirement to the electric supply installation and increases the cost of the ONU.
The existing related technologies do not provide a method to solve the problem mentioned above.